Rollup merge of #148502 - tshepang:rdg-sync, r=tshepang

rustc-dev-guide subtree update

Subtree update of `rustc-dev-guide` to rust-lang/rustc-dev-guide@1a96e5e.

Created using https://github.com/rust-lang/josh-sync.

r? `@ghost`

Author: Zalathar